Multiple flash bulb device

ABSTRACT

A multiple flash bulb device embodying a number of flash bulbs which can be individually connected through the agency of a stepping mechanism with a voltage source incorporating a capacitor which can be charged via a charging resistor, and wherein the flash bulbs can be ignited by a flash contact. An actuation magnet is operatively associated with the stepping mechanism, the power for operating the actuation magnet being furnished by the supply source and the actuation magnet can be connected into the circuit via the flash contact. An electrical valve is connected in series with the actuation magnet, this electrical valve can be brought into a conductive state through the agency of a time-delay element which can be activated by the flash contact.

United States Paten Von Gunten et al. 1

[54] MULTIPLE FLASH BULB DEVICE [75] Inventors: Adeline Von Gunten, Murten; Gabriel Schwarzkopf, Biel, both of Switzerland [73] Assignee'. Fotostudio Von Gunten & Senn,

Murten, Freiburg, Switzerland [22] Filed: April 26, 1971 [21] Appl. No.: 137,512

[30] Foreign Application Priority Data April 30, 1970 Switzerland ..6571/70 [52] U.S.Cl ..240/1.3 [51] Int. Cl. ..G03b 15/02, HOSb 41/02 [58] Field of Search ..240/1.3

[56] References Cited UNITED STATES PATENTS 3,517,595 6/1970 Wagner et al. ..240/1.3 X 3,263,068 7/1966 Jakob ..240/l.3 3,466,992 9/1969 Wick et al. 30

1 1 Jan. 30, 1973 3,514,587 5/1970 Engelsmann ct al. ..240/l.3

Primary Examiner-Louis R. Prince Assistant Examiner-Joseph W. Roskos Attorney-Richard P. Alberi [57] ABSTRACT A multiple flash bulb device embodying a number of flash bulbs which can be individually connected through the agency of a stepping mechanism with a voltage source incorporating a capacitor which can be charged via a charging resistor, and wherein the flash bulbs can be ignited by a flash contact. An actuation magnet is operatively associated with the stepping mechanism, the power for operating the actuation magnet being furnished by.the supply source and the actuation magnet can be connected into the circuit via the flash contact. An electrical valve is connected in series with the actuation magnet, this electrical valve can be brought into a conductive state through the agency of a time-delay element which can be activated by the flash contact.

9 Claims, 4 Drawing Figures MULTIPLE FLASH BULB DEVICE BACKGROUND OF THE INVENTION The present invention relates to a new and improved type of multiple flash bulb device of the type equipped with a number of flash bulbs which can be individually connected through the agency of an indexing or stepping mechanism with a voltage source incorporating a capacitor which can be charged via a charging resistor, and wherein the flash bulbs can be ignited by means of a flash contact, and further wherein the stepping mechanism has associated therewith an actuation magnet supplied by the voltage source and capable of being connected into the circuit via the flash contact.

Flash bulb devices utilizing a number of flash bulbs have again gained considerable importance owing to the worldwide dissemination of the so-called flash bulb cubes" which can be thrown away. This is so regardless of whether the flash bulb device is a separate attachment for the camera or is an integral part of the camera housing. With these type flash bulb devices, each time that a flash bulb fires the next flash bulb must be placed in a preparatory position, for instance the flash bulb cube must be rotated.

In devices which are built into the camera or photographic instrument, it is known to manually advance or index the flash bulb cube by means of a mechanism which is operatively coupled with the film feed or advancing knob.

This technique of simultaneously placing the next flash bulb in its preparatory position along with the actuation of the film advancing or feed knob is, however, only sensible in the case of flash bulb circuits which are installed at the camera. Furthermore, coupling of the film feed action and the indexing of the flash bulb with one another does not allow for double exposure, sometimes desirable for achieving certain effects. Furthermore, connecting an additional mechanism with the film advancing knob does not exactly improve its easy action. In the case of flash bulb devices which are separate from the camera, in other words in the form of attachments for the camera, advancing or indexing of the flash bulbs initially occurs by actuating a special knob or lever.

Due to the recognition in the art that coupling the action of the film feed and the indexing or advance of the flash bulbs is not very practical, and furthermore, it is only sensible for flash bulb devices which are part of the camera, there has previously been proposed an automatic stepping or indexing mechanism which is activated upon closing of a flash bulb contact, herein merely conveniently referred to as a flash contact. A known device operating in accordance with this principle has been disclosed in German Pat. No. 1,206,726.

In this known device it is possible to connect directly with the voltage source, by means of the flash contact, both the flash bulb which is then located in its preparatory position as well as also the actuation magneLl-Iowever, such a circuit arrangement is then only reliable if for certainty the response time of the actuation magnet is a multiple of the response time of the flash bulb. If this is not the case then the danger exists that the flash bulb will be indexed, and thus its supply of power interrupted, before the flash bulb has actually finished firing. Additionally, the need to simultaneously and directly switch-on both the flash bulb as well as the actuation magnet requires a correspondingly larger design of the current source and the flash-contact in order to prevent contact pitting, so that the entire device becomes heavier and the flash contact more cumbersome.

SUMMARY OF THE INVENTION Accordingly, there is still present a real need in the art for a multiple flash bulb device which is not associated with the aforementioned drawbacks of the prior art constructions discussed above. Hence, a primary object of the present invention is to provide such multiple flash bulb device which capably and reliably fulfills the existing need in the art and overcomes the aforediscussed drawbacks.

Another and more specific object of the present invention relates to a novel type of multiple flash bulb device which is relatively simple in construction, extremely reliable in operation, economical to manufacture, compact, not readily subject to breakdown, and ensures for positive and reliable firing of each flash bulb.

Still a further significant object of the present invention is the provision of a multiple flash bulb device incorporating novel circuitry for ensuring completion of the firing of each flash bulb prior to placement of a new flash bulb into its preparatory position for firing.

Now in keeping with the aforementioned objectives, it is contemplated by the invention to initiate switchingin of the actuation magnet still through the action of the flash contact, but energy is first then positively delivered to the actuation magnet when the firing or ignition of the flash bulb has been completed.

The invention is based upon the recognition that at a circuit junction or terminal between the charging resistor and the capacitor of the voltage supply there occurs during the ignition of the flash bulb a characteristic voltage curve or course which repeatseach time a flash bulb is ignited or fired.

Accordingly, the invention proposes a multiple flash bulb device of the aforementioned type which employs circuitry wherein an electrical valve is connected in series with the actuation magnet, this electrical valve can be caused to become activated or conduct through the agency of a time-delay element which can be actuated via the flash contact. It is to be understood that in the context of this application the term valve" as used herein is intended to encompass not only electronictubes but also solid state or semiconductor devices.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein:

FIG. 1 schematically illustrates the mechanical hardware of an indexing or stepping mechanism for a flash bulb cube;

FIG. 2 is a first embodiment of electric circuitry for supplying the flash bulbs with power and for controlling an actuation magnet for indexing the flash bulb cube;

FIG. 3 is a second embodiment of circuitry which can be used with the arrangement of FIG. 1, and

wherein serving as the electronic switch or electrical valve there is used a thyristor; and

FIG. 4 is a circuit diagram of a further embodiment of electrical circuitry for use in conjunction with the arrangement of FIG. I, and wherein serving as the electrical valve there is used a unijunction transistor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in the arrangementof FIG. I there is shown the most significant components of a mechanical indexing or stepping mechanism for use in conjunction with, for instance, a flash bulb cube having a number of individual flash bulbs. Thus, more particularly there will be seen that such stepping mechanism embodies a flash bulb cube-releasable locking or arresting mechanism 2 incoporating a ratchet wheel or disc 1 equipped with four teeth la. Ratchet wheel 1 is mounted to be rotatable about an axis 4 and is pre-biased by a spiral spring 3 which is fixedly clamped at location 5, pre-biasing of the ratchet wheel 1 being undertaken such that this ratchet wheel has the tendency of rotating in the direction of the arrow 15. The spiral spring 3 is intended to conceptually portray a mechanical force storage device of any suitable type, for instance a spring wound mechanism with reduction gearing. The ratchet wheel 1 forms a component of a non-illustrated socket for receiving a standard flash bulb cube and is rotatably coupled with such socket.

In the illustration of FIG. 1 the ratchet wheel 1 is prevented from roatating by the impact or stop surface 8 of a three-arm arresting armature 6 pivotably mounted at location 7. This arresting armature 6 possesses a further stop or impact surface 9 which in the illustration of FIG. 1 is not in its operable position. The stop or impact surfaces 8 and 9 are located at respective ones of two of the three arms of the three-arm arresting armature. The third arm of this arresting armature 6 is pivotably connected on the one hand with the armature or core 11 of a magnetic coil 12 and on the other hand is pivotably connected at location with a tension spring 14. The leads or connections 13 serve to furnish power to the magnetic coil 12 for the'purpose of placing such in an excited or energized state.

Now if the magnetic coil 12 is furnished with a current surge in a manner still to be described, then, the armature or coil 1 l is attracted against the action of-the spring 14. As a result thethree-arm armature or lever 6 is rocked in counterclockwise direction, resulting in the stop surface 8 being brought out of the operable zone of the contacting tooth or finger la of the ratchet wheel 1, whereas the other stop or impact surface 9 is brought into the operable zone of the ratchet wheel tooth 1a which is located lowermost in the showing of FIG. 1. Hence, the spring-loaded ratchet wheel 1 will rotate to the extent permitted by the stop surface 9. Upon completion of the current surge delivered to the magnetic coil 12 the spring 14 causes the armature 6 to rock in the clockwise direction back into its starting position, resulting in the stop surface 8 coming into engagement with the next successive ratchet wheel tooth la, namely the tooth which is shown at the far left of the ratchet wheel 1 of FIG.'1. From what has been explained above it will be understood that each time a current surge is delivered to the magnetic coil 12 the indexing ratchet wheel I and therefore also the flash bulb cube, shown in FIGS. 2-4 at B, which is rigidly connected for rotation therewith is rotated through approximately 90, and this occurs as long as the spring 3 is in a tensioned or biased state.

The invention contemplates novel circuitry, as shown in FIGS. 2, 3 and 4, intended to demonstrate the manner in which it is possible to produce the current surges needed to index or advance the flash bulb cube. Each circuit under consideration and to be described hereinafter is designed in such a way to ensure that completion of the ignition or firing of each flash bulb occurs before the indexing of the multiple flash bulb takes place.

Referring now to the exemplary embodiment of circuitry depicted in FIG. 2 it will be seen that a power source, for instance the voltage source 27, which may be constituted by a dry battery or a rechargable accumulator, serves to maintain in a charged condition a capacitor 26 via a charging resistor 25. Arranged in the discharging circuit of the capacitor 26 is a flash bulb B which is connected into the circuit via the contacts 20 and 21 and there is also provided at such discharge circuit a flash bulb-or flash contact 24. The flash contact 24 is typically located at the closure mechanism of the camera and therefore is electrically coupled into the discharge circuit via the plug connections 22 and the cable 23. What has been described above constitutes circuitry which in principle is present for almost all conventional flash bulb devices. It is to be observed that in the first instance the capacitor 26 serves as the I voltage source for the flash bulb B. The energy of the capacitor 26, upon closing the contact 24, is discharged directly and in a surge-like fashion across the flash bulb B, resulting in its glow or incandescent filament being caused to fire or ignite.

Now between the charging resistor 25 and the capacitor 26 there appears the circuit junction or point A. The base electrode 30 of a conventional npntransistor 29 is connected with this circuit point A through the agency of a resistor 28. The emitter 31 of this transistor 29 is connected to the negativeterminal of the current source 27 and the collector 32 is connected via the magnetic coil 12 to the positive terminal or pole of the current source 27. From what'has been described above it will be understood that transistor 29 functions as an electronic switch in the illustrated circuitry, blocking a current flow between the collector and emitter as long as the base 30 of the transistor 29 is sufficiently negatively prebiased with respect to the collector 32.

Now the mode of operation of the described circuitry is as follows: as long as the flash or'flash bulb contact 24 is open the current source 27 charges the capacitor.

'base electrode 30 of the transistor 29 then is at the same potential as the circuit point A, transistor 29 functioning as an open switch and preventing current flow through the magnetic coil 12.

Now if the flash contact 24 is closed, then the following operations occur: the capacitor 26 discharges in a surge-like fashion (there is no particular discharge resistor present) across the flash bulb B which is then caused to ignite or fire. At the same time the voltage at the capacitor 26 collapses and in the charging circuit current again begins to flow, which in the first moment of charging it is practically only limited by the charging resistor 25. Now since a current flows through this resistor 25 the circuit point A shifts to a higher potential, governed by the voltage drop across the resistor 25, than prior to ignition of the flash bulb B. The base 30 of the transistor 29 is also then at this higher potential. Consequently, the transistor 29 is now rendered conductive, that is, a current flows between the collector 32 and the emitter 31, whereby the magnetic coil 12 is placed into circuit with the voltage of the battery 27 and the armature or coil 1 l is energized. As previously explained there is thus initiated the indexing or stepping of the flash bulb B.

The operations which have been described up to now last for a small faction of a second. Since the charging current flowing to the capacitor 26 decays to zero in accordance with an exponential function which is dependent upon time as well as upon the value of the charging resistance 25 and the capacitance of the capacitor 26 the potential difference between the circuit point A and the negative pole of the current source also decays to zero or null. Consequently, the base 30 of the npn-transistor 29 is again negatively biased, the transistor blocks, and the current supply to the magnetic coil 12 is again interrupted. As a result the starting condition is again present, especially since stepping mechanism triggered by the magnetic coil 12 electrically couples a new flash bulb with the contacts 20, 21.

It is of course here to be mentioned that for the circuitry illustrated in FIG. 2 it would also be possible to use a pnp-transistor, whereby, then, of course the voltage source 27 must be reversed in polarity since such type transistor is conductive when the base is negatively pre-biased.

Turning now to FIG. 3 there is shown a modified form of electrical circuitry for the multiple flash bulb device of the invention wherein, here, there is used as the electrical valve a thyristor. Once again in this circuit of FIG. 3 there will be recognized the battery 27, at the positive pole of which there is connected the charging resistor 25 and in series with this resistor 25 the capacitor 26. A conductor 41 leads from the capacitor 26 back to the negative pole of the battery 27. Both terminals of the capacitor 26 are bridged by the flash contact 24 connected via the plug connection 22 and the series connected flash bulb B coupled with the contacts 21, 20, so that upon closing the flash contact 24 the energy stored at the charged capacitor 26 discharges in surge-like fashion across the bulb B.

The coil 12 of the actuation magnet is likewise connected electrically with the battery 27. Connected in series with the actuation magnet is a thyristor 33 having an anode 39, cathode 38 and a controlor gate-electrode 37. A lead or conductor 42 extends from the cathode 38 via a rest contact 36the significance of which will be described more fully hereinafterback to the battery 27, as shown. The control electrode 37 is electrically coupled via a conductor 43 and a resistor 34 with the circuit pointor junction C which, in turn, is

coupled via the flash contact 24 with the circuit point A between the charging resistor 25 and the capacitor 26. A capacitor 35 is connected between the conductor 43 and the negative pole of the battery 27, capacitor 35 together with the resistor 34 forming a time-delay element.

The mode of operation of this circuitry is as follows: in the rest state. of the circuit the capacitor 26 is charged via the charging resistor 25'. Prior to closing the flash or flash bulb contact 24, that is in the rest state, the circuit point C is maintained at negative potential because it is in direct connection. with the negative pole of the battery 27 via the incandescent or heated filament of the flash bulb B, contact 20 and conductor 41. Upon closing the flash contact 24 the flash bulb B ignites and the potential of the circuit point C suddenly becomes positive, because this circuit point is then connected via the resistor 25 (as long as the flash contact 24 is closed) with the positive pole of the battery 27.

However if the potential at the circuit point C changes, then the potential of the conductor 43 leading to the control electrode 37 also changes, but in the circuitry under consideration in the present case with a time-delay however, which is determined by the timedelay element formed of the resistor 34 and the capacitor 35. In the rest state, that is as long as the circuit point C and together with such the conductor 43 and the control electrode 37 are negatively biased, then the thyristor 33 is not conductive. On the other hand, if the control electrode 37 reaches a positive potential corresponding to the ignition voltage of the thyristor 33, then thyristor 33 ignites, that is, suddenly becomes conductive and thereby electrically couples the coil 12 with the supply battery 27. As described, the control electrode 37 becomes positive upon closing the contact 24 after a certain time delay defined by the time-delay element. Consequently, the thyristor 33 likewise fires with a certain time-delay and similarly the actuation magnet 12 also is placed into operation with a certain time-delay. However, since a thyristor remains conductive once it has been fired, even if the voltage of the control electrode falls below the ignition voltage, it is necessary to provide the rest contact 36 which is mechanically coupled, as schematically indicated at 40, with the indexing or stepping mechanism, for instance with the indexing ratchet wheel 1 or with the locking armature 6, and is opened by such mechanism. In this way measures have been provided for interrupting the current flow through the coil 12 and the thyristor 33 shortly after ignition of the thyristor, so that the rest condition can again be established, but of course with a new flash bulb having in the meantime been coupled into its preparatory position for firing.

FIG. 4 illustrates a further modification of circuitry of the invention which uses a unijunction transistor as the electronic switching element. Here also there will be recognized the battery 27, resistor 25, capacitor 26,

the flash bulb B, as well as the flash contact 24 which were previously present as circuit components in the circuitry of FIGS. 2 and 3. There will also be recognized the coil 12.

The new components of this circuit are the unijunction transistor 45, two resistors 47 and 46, the capacitor 48, and the switch 49. It the switch 49 is closed then the battery 27 can charge the capacitor 26 by means of the resistor 25. The point D of the capacitor 26 is practically coupled with the negative pole of the battery 27 since the incandescent wire or filament of the flash bulb possesses a very small resistance. in order to fire or ignite the flash bulb here also the contact 24 of the camera is closed, whereby the capacitor 26 discharges in surge-like fashion and causes the incandescent filament of the flash bulb or flashlight lamp to ignite.

As soon as the flash bulb B has ignited then the shortcircuit, formed by its incandescent wire or filament via the capacitor 48, is removed. The capacitor 48 can now be charged via the resistor 46, both of these circuit components possessing a certain time constant which provide the necessary time-delay after firing of the flash bulb in order to allow the flash bulb cube to be further rotated.

As soon as the capacitor 48 has charged to a certain voltage, that is, as soon as the voltage at the emitter E of the transistor 45 has become sufficiently positive then the transistor 45 ignites. As a result, the energy which has been stored at the capacitor 48 can suddenly discharge across the base connection 50 of the transistor 45 and thus pulse-like excite or energize the coil 12. As a result the stepping or indexing mechanism described in conjunction with FIG. 1 is brought into operation. The resistor 47 is necessary for the current supply of the transistor 45. With the above-described circuit excitation of the electromagnet occurs periodically if there is not connected any non-ignited flash bulb. It is for that reason that the switch 49 is necessary. it also serves to save on current during non-operation, since a small rest current always flows across the resistor 46 and the incandescent filament of the flash bulb B which discharges the battery 27.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Ac-

a voltage source;

a charging network including a capacitor and charging resistor through which said capacitor is chargeable by said voltage source;

a flash bulb contact connected to discharge said capacitor through said flash bulb and said flash bulb contact, when actuated; and

an electronic switch means operative when closed to actuate said stepping mechanism;

said electronic switch means coupled to and responsive to said charging network to close said electronic switch after a time delay determined by the charginfi characteristics of said charging network, and o ereby'advance said stepping mechanism to index a fresh flash bulb into position.

2.-The multiple flash bulb device as defined in claim 1, wherein said electronic switch means comprises a solid state device.

3. The multiple flash bulb device as defined in claim 1, wherein said stepping mechanism includes actuation magnet means energizable by said electronic switch means, a loaded indexing plate, and blocking armature means operatively coupled with said actuation magnet means for selectively indexing said indexing plate.

4. The multiple flash bulb device as defined in claim 3, wherein said transistor is a npn-transistor.

5. The multiple flash bulb device as defined in claim 3, wherein said transistor is a pnp-transistor.

6. The multiple flash bulb device as defined in claim 2, wherein said solid state device comprises a transistor having a base electrically coupled in said electric circuit between the circuit junction between said charging resistor and said capacitor.

7. The multiple flash bulb device as defined in claim 5, wherein said number of flash bulbs is constituted by a flash bulb cube operatively connected for rotation with said indexing plate.

8. The multiple flash bulb device as defined in claim 2, wherein said solid state device comprises a thyristor having a control electrode, said electric circuit further including means for connecting said control electrode of said thyristor with the circuit junction between said charging resistor and said capacitor, a battery, said flash bulb contact being in circuit with said flash bulbs, said charging resistor and said capacitor being connected in series between one pole of said battery and the connection of said flash bulbs with said flash contact.

9. The multiple flash bulb device as defined in claim 1, wherein said solid state device comprises a unijunction transistor. 

1. In a multiple flash bulb device having a number of flash bulbs and comprising a stepping mechanism opeRatively associated with said flash bulbs for indexing said flash bulbs after ignition of one of said flash bulbs to place a new flash bulb in a preparatory position for ignition, the improvement comprising an electric circuit for selectively supplying power to individual ones of said flash bulbs and to operate said stepping mechanism after fully energizing each bulb, said electric circuit comprising: a voltage source; a charging network including a capacitor and charging resistor through which said capacitor is chargeable by said voltage source; a flash bulb contact connected to discharge said capacitor through said flash bulb and said flash bulb contact, when actuated; and an electronic switch means operative when closed to actuate said stepping mechanism; said electronic switch means coupled to and responsive to said charging network to close said electronic switch after a time delay determined by the charging characteristics of said charging network, and to thereby advance said stepping mechanism to index a fresh flash bulb into position.
 1. In a multiple flash bulb device having a number of flash bulbs and comprising a stepping mechanism opeRatively associated with said flash bulbs for indexing said flash bulbs after ignition of one of said flash bulbs to place a new flash bulb in a preparatory position for ignition, the improvement comprising an electric circuit for selectively supplying power to individual ones of said flash bulbs and to operate said stepping mechanism after fully energizing each bulb, said electric circuit comprising: a voltage source; a charging network including a capacitor and charging resistor through which said capacitor is chargeable by said voltage source; a flash bulb contact connected to discharge said capacitor through said flash bulb and said flash bulb contact, when actuated; and an electronic switch means operative when closed to actuate said stepping mechanism; said electronic switch means coupled to and responsive to said charging network to close said electronic switch after a time delay determined by the charging characteristics of said charging network, and to thereby advance said stepping mechanism to index a fresh flash bulb into position.
 2. The multiple flash bulb device as defined in claim 1, wherein said electronic switch means comprises a solid state device.
 3. The multiple flash bulb device as defined in claim 1, wherein said stepping mechanism includes actuation magnet means energizable by said electronic switch means, a loaded indexing plate, and blocking armature means operatively coupled with said actuation magnet means for selectively indexing said indexing plate.
 4. The multiple flash bulb device as defined in claim 3, wherein said transistor is a npn-transistor.
 5. The multiple flash bulb device as defined in claim 3, wherein said transistor is a pnp-transistor.
 6. The multiple flash bulb device as defined in claim 2, wherein said solid state device comprises a transistor having a base electrically coupled in said electric circuit between the circuit junction between said charging resistor and said capacitor.
 7. The multiple flash bulb device as defined in claim 5, wherein said number of flash bulbs is constituted by a flash bulb cube operatively connected for rotation with said indexing plate.
 8. The multiple flash bulb device as defined in claim 2, wherein said solid state device comprises a thyristor having a control electrode, said electric circuit further including means for connecting said control electrode of said thyristor with the circuit junction between said charging resistor and said capacitor, a battery, said flash bulb contact being in circuit with said flash bulbs, said charging resistor and said capacitor being connected in series between one pole of said battery and the connection of said flash bulbs with said flash contact. 